Search

Your search keyword '"Wiens, Roger C."' showing total 16 results
Start Over Author "Wiens, Roger C." Journal icarus
16 results on '"Wiens, Roger C."'

3. The SuperCam infrared spectrometer for the perseverance rover of the Mars2020 mission

Author

Fouchet, Thierry, Reess, Jean-Michel, Montmessin, Franck, Hassen-Khodja, Rafik, Nguyen-Tuong, Napoléon, Humeau, Olivier, Jacquinod, Sophie, Lapauw, Laurent, Parisot, Jérôme, Bonafous, Marion, Bernardi, Pernelle, Chapron, Frédéric, Jeanneau, Alexandre, Collin, Claude, Zeganadin, Didier, Nibert, Patricia, Abbaki, Sadok, Montaron, Christophe, Blanchard, Cyrille, Arslanyan, Vartan, Achelhi, Ourdya, Colon, Claudine, Royer, Clément, Hamm, Vincent, Beuzit, Mehdi, Poulet, François, Pilorget, Cédric, Mandon, Lucia, Forni, Olivier, Cousin, Agnès, Gasnault, Olivier, Pilleri, Paolo, Dubois, Bruno, Quantin, Cathy, Beck, Pierre, Beyssac, Olivier, Le Mouélic, Stéphane, Johnsson, Jeffrey R., McConnochie, Timothy H., Maurice, Sylvestre, and Wiens, Roger C.

Published
2022
Full Text
View/download PDF

5. Origin and composition of three heterolithic boulder- and cobble-bearing deposits overlying the Murray and Stimson formations, Gale Crater, Mars

Author

Wiens, Roger C., Edgett, Kenneth S., Stack, Kathryn M., Dietrich, William E., Bryk, Alexander B., Mangold, Nicolas, Bedford, Candice, Gasda, Patrick, Fairén, Alberto, Thompson, Lucy, Johnson, Jeff, Gasnault, Olivier, Clegg, Sam, Cousin, Agnes, Forni, Olivier, Frydenvang, Jens, Lanza, Nina, Maurice, Sylvestre, Newsom, Horton, Ollila, Ann, Payré, Valerie, Rivera-Hernandez, Frances, and Vasavada, Ashwin

Published
2020
Full Text
View/download PDF

9. Centimeter to decimeter hollow concretions and voids in Gale Crater sediments, Mars

Author

Wiens, Roger C., Rubin, David M., Goetz, Walter, Fairén, Alberto G., Schwenzer, Susanne P., Johnson, Jeffrey R., Milliken, Ralph, Clark, Ben, Mangold, Nicolas, Stack, Kathryn M., Oehler, Dorothy, Rowland, Scott, Chan, Marjorie, Vaniman, David, Maurice, Sylvestre, Gasnault, Olivier, Rapin, William, Schroeder, Susanne, Clegg, Sam, Forni, Olivier, Blaney, Diana, Cousin, Agnes, Payré, Valerie, Fabre, Cecile, Nachon, Marion, Le Mouelic, Stephane, Sautter, Violaine, Johnstone, Stephen, Calef, Fred, Vasavada, Ashwin R., and Grotzinger, John P.

Published
2017
Full Text
View/download PDF

11. Gale crater and impact processes – Curiosity’s first 364 Sols on Mars

Author

Newsom, Horton E., Mangold, Nicolas, Kah, Linda C., Williams, Joshua M., Arvidson, Ray E., Stein, Nathan, Ollila, Ann M., Bridges, John C., Schwenzer, Susanne P., King, Penelope L., Grant, John A., Pinet, Patrick, Bridges, Nathan T., Calef, Fred, III, Wiens, Roger C., Spray, John G., Vaniman, David T., Elston, Wolf E., Berger, Jeff A., Garvin, James B., and Palucis, Marisa C.

Published
2015
Full Text
View/download PDF

12. Understanding the signature of rock coatings in laser-induced breakdown spectroscopy data

Author

Lanza, Nina L., Ollila, Ann M., Cousin, Agnes, Wiens, Roger C., Clegg, Samuel, Mangold, Nicolas, Bridges, Nathan, Cooper, Daniel, Schmidt, Mariek, Berger, Jeffrey, Arvidson, Raymond, Melikechi, Noureddine, Newsom, Horton E., Tokar, Robert, Hardgrove, Craig, Mezzacappa, Alissa, Jackson, Ryan S., Clark, Benton, Forni, Olivier, Maurice, Sylvestre, Nachon, Marion, Anderson, Ryan B., Blank, Jennifer, Deans, Matthew, Delapp, Dorothea, Léveillé, Richard, McInroy, Rhonda, Martinez, Ronald, Meslin, Pierre-Yves, and Pinet, Patrick

Published
2015
Full Text
View/download PDF

13. Retrieval of Water Vapor Column Abundance and Aerosol Properties from ChemCam Passive Sky Spectroscopy

Author

Mcconnochie, Timothy H, Smith, Michael D, Wolff, Michael J, Bender, Steve, Lemmon, Mark, Wiens, Roger C, Maurice, Sylvestre, Gasnault, Olivier, Lasue, Jeremie, Meslin, Pierre-Yves, Harri, Ari-Matti, Genzer, Maria, Kemppinen, Osku, Martinez, German M, DeFlores, Lauren, Blaney, Diana, Johnson, Jeffrey R, and Bell, James F

Subjects
Earth Resources And Remote Sensing
Abstract

We derive water vapor column abundances and aerosol properties from Mars Science Laboratory (MSL) ChemCam passive mode observations of scattered sky light. This paper covers the methodology and initial results for water vapor and also provides preliminary results for aerosols. The data set presented here includes the results of 113 observations spanning from Mars Year 31 L(s) = 291 deg (March 30, 2013) to Mars Year 33 L(s) = 127 deg (March 24, 2016). Each ChemCam passive sky observation acquires spectra at two different elevation angles. We fit these spectra with a discrete-ordinates multiple scattering radiative transfer model, using the correlated-k approximation for gas absorption bands. The retrieval proceeds by first fitting the continuum of the ratio of the two elevation angles to solve for aerosol properties, and then fitting the continuum-removed ratio to solve for gas abundances. The final step of the retrieval makes use of the observed CO 2 absorptions and the known CO 2 abundance to correct the retrieved water vapor abundance for the effects of the vertical distribution of scattering aerosols and to derive an aerosol scale height parameter. Our water vapor results give water vapor column abundance with a precision of +/-0.6 precipitable microns and systematic errors no larger than +/-0.3 precipitable microns, assuming uniform vertical mixing. The ChemCam-retrieved water abundances show, with only a few exceptions, the same seasonal behavior and the same timing of seasonal minima and maxima as the TES, CRISM, and REMS-H data sets that we compare them to. However ChemCam-retrieved water abundances are generally lower than zonal and regional scale from-orbit water vapor data, while at the same time being significantly larger than pre-dawn REMS-H abundances. Pending further analysis of REMS-H volume mixing ratio uncertainties, the differences between ChemCam and REMS-H pre-dawn mixing ratios appear to be much too large to be explained by large scale circulations and thus they tend to support the hypothesis of substantial diurnal interactions of water vapor with the surface. Our preliminary aerosol results, meanwhile, show the expected seasonal pattern in dust particle size but also indicate a surprising interannual increase in water-ice cloud opacities.

Published
2017
Full Text
View/download PDF

15. Gale Crater and Impact Processes - Curiosity's First 364 Sols on Mars

Author

Newsom, Horton E, Mangold, Nicolas, Kah, Linda C, Williams, Joshua M, Arvidson, Ray E, Stein, Nathan, Ollila, Ann M, Bridges, John C, Schwenzer, Suzanne P, King, Penelope L, Grant, John A, Pinet, Patrick, Bridges, Nathan T, Calef, Fred, III, Wiens, Roger C, Spray, John G, Vaniman, David T, Elston, Wolf E, Berger, Jeff A, Garvin, James B, and Palucis, Marisa C

Subjects
Lunar And Planetary Science And Exploration
Abstract

Impact processes at all scales have been involved in the formation and subsequent evolution of Gale crater. Small impact craters in the vicinity of the Curiosity MSL landing site and rover traverse during the 364 Sols after landing have been studied both from orbit and the surface. Evidence for the effect of impacts on basement outcrops may include loose blocks of sandstone and conglomerate, and disrupted (fractured) sedimentary layers, which are not obviously displaced by erosion. Impact ejecta blankets are likely to be present, but in the absence of distinct glass or impact melt phases are difficult to distinguish from sedimentary/volcaniclastic breccia and conglomerate deposits. The occurrence of individual blocks with diverse petrological characteristics, including igneous textures, have been identified across the surface of Bradbury Rise, and some of these blocks may represent distal ejecta from larger craters in the vicinity of Gale. Distal ejecta may also occur in the form of impact spherules identified in the sediments and drift material. Possible examples of impactites in the form of shatter cones, shocked rocks, and ropy textured fragments of materials that may have been molten have been observed, but cannot be uniquely confirmed. Modification by aeolian processes of craters smaller than 40 m in diameter observed in this study, are indicated by erosion of crater rims, and infill of craters with aeolian and airfall dust deposits. Estimates for resurfacing suggest that craters less than 15 m in diameter may represent steady state between production and destruction. The smallest candidate impact crater observed is ∼0.6 m in diameter. The observed crater record and other data are consistent with a resurfacing rate of the order of 10 mm/Myr; considerably greater than the rate from impact cratering alone, but remarkably lower than terrestrial erosion rates.

Published
2014
Full Text
View/download PDF

16. Sputtering products of sodium sulfate: implications for Io's surface and for sodium-bearing molecules in the Io Torus

Author

Wiens, Roger C., Burnett, D.S., Calaway, W.F., Hansen, C.S., Lykke, K.R., and Pellin, M.J.

Subjects
Sodium sulfate -- Observations, Io (Satellite) -- Observations, Molecules -- Observations, Astronomy, Earth sciences
Abstract

The composition of the sodium-bearing molecular ion cloud in the vicinity of Io may yield clues to Io's geochemistry. Likely Na-bearing source minerals are Na-sulfides and [Na.sub.2]S[O.sub.4], with the relative composition depending on the distribution of thermal environments in the upper crust. These materials will be sputtered by co-rotating torus ions either from the surface or from atmospheric aerosols. Using laser postionization, we investigated the ion-sputtered neutral products of [N.sub.2]S[O.sub.4] to determine whether NaO in the Io torus might be a diagnostic indicator for sodium sulfate on Io's surface or in aerosols. With an ArF excimer laser ([Lambda] = 6.4 eV), single-photon saturation of the ionization step was achieved for NaS, [Na.sub.2]O, and the combination [Na.sub.2]S + [Na.sub.2][O.sub.2] at mass 78, while other species, including NaO, were close to saturation. Photofragmentation during the ionization step was minimal by all indications. The results predict sputtering ratios NaO/NaS > 8, [Na.sub.2]O/NaS [approximately]8, [Na.sub.2]/NaS [greater than or equal to] 6, and Na/NaS [greater than or equal to] 100. Multiphoton ionization was also attempted using a frequency-doubled (3.2-eV) Ti:sapphire femtosecond laser at high intensities, but saturation was not achieved for the major species, and there was evidence of photofragmentation. Velocity distributions of the sputter products show for the first time that significant fractions of sodium-bearing molecules can be sputtered into unbound trajectories from Io's surface, with escape fractions > 50% in the case of NaO. Combining relative sputter yields and velocity distributions gives escape ratios of NaO/NaS > 10, Na:/NaS [approximately]6, and [Na.sub.]O/NaS [approximately]2.8 from [Na.sub.2]S[O.sub.4]. While absolute sputtering and escape ratios need to be compared for Na-sulfides versus [Na.sub.2]S[O.sub.4], this work shows that, in the absence of significant modification by atmospheric chemical reactions, measurement of the neutral NaO/NaS ratio in the vicinity of Io could identify the major Na-bearing minerals.

Published
1997

Catalog

Books, media, physical & digital resources
See catalog results